This invention relates generally to improvements in door latch and related latch bolt operators for retracting one or more latch bolts on a door, such as an entry door for a residence or business establishment. More specifically, this invention relates to an improved door latch operator designed primarily for use with a multipoint latch bolt system of the general type disclosed in U.S. Pat. No. 5,290,077, wherein multiple latch bolts are mounted along a free side edge of the door for respective engagement with multiple associated strike sets on the adjacent doorjamb. The door latch operator of the present invention facilitates concurrent operative retraction of multiple latch bolts to accommodate relatively quick and easy opening of the door.
Door latch and lock assemblies for use with hinged swinging doors are generally known in the art, and typically include at least one movable lock member mounted at a selected vertical position along a free side edge of the door in proximity with an actuator positioned for convenient manual access and operation. For example, a spring-loaded latch bolt is normally mounted on the door at a mid-height position to engage a strike or keeper plate mounted on the adjacent doorjamb, to retain the door in a normal closed position. A rotary handle or lever is commonly included as part of the latch and lock assembly, and is adapted for manual rotation to retract the latch bolt from the strike plate and thereby permit the door to be opened. In some door hardware designs, such as typically higher-end hardware, the rotary handle or lever is replaced by a relatively large and more decorative fixed handle in combination with a relatively small actuator lever positioned for thumb-depression to retract the latch bolt. These lock assemblies further include at least one lock device which may be designed to preclude latch bolt retraction in the locked condition, and/or may comprise a separate dead bolt for use in selectively locking the door.
Although such conventional door latch and lock assemblies as described above have generally performed their latching and/or locking functions in a satisfactory manner, there has been an on-going desire and need for further improvements in entry door security for residences and business establishments. Toward this end, so-called multipoint lock assemblies have been developed wherein multiple lock members such as multiple retractable latch bolts are provided at vertically spaced positions along the free side edge of the door for engaging a corresponding number of strike plates mounted at corresponding positions on the adjacent doorjamb. In some designs, the multiple lock members are adapted for independent actuation, with the unfortunate result that frequently only one of the lock members is engaged due to human forgetfulness and/or neglect. In other designs, the multiple lock members are adapted for concurrent actuation by means of a single rotary-mounted operator handle or lever.
U.S. Pat. No. 5,290,077 discloses an exemplary multipoint door lock assembly including multiple retractable latch bolts mounted at vertically spaced positions along the free side edge of an entry door or the like. A primary latch bolt is positioned generally at a mid-height location in close proximity with an actuator mechanism. A pair of secondary latch bolts are respectively positioned vertically above and below the primary latch bolt, and are linked by slide-mounted extension rods with the actuator mechanism. A rotary-mounted lever handle or the like at an outboard side of the door is manually grasped and rotated to operate the actuator mechanism to retract all three latch bolts in a concurrent manner. When the rotary lever handle is released, one or more springs incorporated into the actuator mechanism causes the latch bolts (and lever handle) to return automatically to a normal extended position. As is known in the art, each latch bolt normally includes one tapered face to accommodate automatic retraction as the latch bolt engages the associated strike plate during door closure movement, followed by automatic spring-loaded re-extension of the latch bolt into a strike plate keeper recess as the door reaches the closed position.
Multipoint door lock assemblies of the type shown and described in U.S. Pat. No. 5,290,077 beneficially provide enhanced security against unauthorized entry or tampering, as well as improved door engagement with associated weatherstripping and the like, and further provide enhanced secure closure in response to relatively high wind loads. As such, these multipoint door lock assemblies are becoming increasingly popular. However, such multipoint mechanisms inherently require a significantly increased application of manual effort or manual force in order to retract the multiple latch bolts, in comparison with a traditional single latch bolt system. This requirement for increased manual actuation force is a particular problem with certain, typically higher-end and increasingly popular door hardware of the type having a large fixed handle and a relatively small thumb-depressed lever actuator. In particular, in such higher-end hardware styles, persons having limited physical strength may be unable to apply sufficient force to the thumb lever to open the door.
There exists, therefore, a need for further improvements in and to door latch operators particularly of the type adapted for concurrently retracting multiple latch bolts in a multipoint system of the shown and described in U.S. Pat. No. 5,290,077, wherein the door latch operator can be opened quickly and easily, and in an intuitively apparent manner, by application of a relatively modest or normal actuation force to facilitate operation by virtually any user. The present invention fulfills these needs and provides further related advantages.